Banned for 15 days for finding, and abusing a dupe bug. He then sold the items to other players in the shop....
The ban time is reduced because I got him to hand the blocks/items that he kept, along with the blocks acquired from a different account he had access to (I said he could get on the other account to do this, so it was fine).
I am seriously pondering this, and what to do in regards to duped item bugs that players have abused time and time again.